Biomedical subjects
Publications and source records attributed to K Kastrup.
Neurophysiological data of two brothers with long-standing cystinosis are presented. Both patients showed a distally symmetrical myopathy affecting the arms more than the legs. Myopathy occurred before the onset of polyneuropathy or signs of central nervous involvement.
The pharmacokinetics of recombinant human insulin-like growth factor I (rhIGF-I) were studied in healthy volunteers and in patients with growth hormone receptor deficiency (GHRD; Laron syndrome). Following single subcutaneous injections of rhIGF-I, 40 and 80 micrograms/kg, to healthy volunteers, the peptide was absorbed slowly, with a maximum concentration reached after about 7 hours. Following daily multiple subcutaneous injections of rhIGF-I, 40 micrograms/kg, trough concentrations of IGF-I were increased by 277 +/- 50 micrograms/l (mean +/- SD) from baseline. IGF-I was thus characterized as a low-clearance peptide, with a clearance and half-life estimated at about 0.20 ml/minute/kg and 20 hours, respectively, in healthy volunteers. The volume of distribution was low, about 0.20-0.36 litres/kg, the bioavailability of subcutaneously administered rhIGF-I was 100%, and the rate of production of IGF-I was estimated to be about 50 micrograms/kg/day (3.5 mg/day). Patients with GHRD had low baseline IGF-I concentrations (30-50 micrograms/l) and a much more rapid turnover of IGF-I compared with that in healthy volunteers. The clearance and half-life of IGF-I were estimated to be about 0.60 ml/minute/kg and 6 hours, respectively. The volume of distribution was about the same as in healthy subjects. Due to the rapid turnover of IGF-I, trough IGF-I concentrations were increased to just above baseline during subcutaneous injections of 40 micrograms/kg once daily for 7 days. The maximum increase in IGF-I levels was 111 +/- 12 micrograms/l and 150 +/- 3 micrograms/l following daily subcutaneous injections of 40 x 1 and 40 x 2 micrograms/kg for 7 days, respectively.
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The variations in incidence rates of insulin-dependent diabetes mellitus (IDDM) in childhood within and between genetically very similar Scandinavian populations and the variations in incidence rates with time are difficult to explain. Epidemiological data show that the incidence of childhood IDDM may now be declining and suggest an inverse correlation between breast-feeding frequency and IDDM in childhood. Case-control data show that diabetic children were breast-fed for shorter periods of time than their healthy siblings and the population at large and that a smaller proportion of diabetic children were ever breast-fed. It is postulated that insufficient breast-feeding of genetically susceptible newborn infants may lead to beta-cell infection and IDDM later in life.
Girls with adolescent idiopathic scoliosis are taller than nonscoliotic girls of the same age. This observation may be related to factors regulating longitudinal growth. Plasma growth hormone was determined in a group of scoliotic girls by double antibody radioimmunoassay under the following conditions: 1) Insulin induced hypoglycemia, 2) glucose tolerance test, 3) exercise. Somatomedin A was determined by a method based on the ability of serum to stimulate the incorporation of radioactive sulphate in embryonic chick cartilage. The results were compared with those obtained in a control group of healthy nonscoliotic girls of comparable age. After overnight fasting and after at least one hour's rest the basal growth hormone level was 9.8+/-11.1 (+/-S.D.) ng/ml in the scoliotic girls (n=48) and 2.2+/-1.1 ng/ml in the controls (n=15). This difference is significant. In the hypoglycemia test the peak growth hormone level tended to be higher in the scoliotic girls but the difference is not significant. In the exercise test the maximal value was reached at different times in the two groups: at 20 min after start of the exercise in the scoliotic girls (n=14, 17.3+/-11.8 ng/ml) and at 40 min in the controls (n=9, 16.0+/-6.6 ng/ml). In the glucose tolerance test the growth hormone level was suppressed in both groups but the mean values tended to be higher during the first 120 min in the scoliotic girls. The serum somatomedin levels were higher in the group of scoliotic girls (n=19, 1.13+/-0.17 U/ml) than in the controls (n=14, 0.88+/-0.16 U/ml) and the difference is significant. The results obtained are difficult to interpret but suggest that growth hormone secretion is higher in girls with adolescent idiopathic scoliosis than in healthy girls of comparable age.